Sadako Sasaki, a 12-year-old Japanese girl who died from radiation-induced leukemia caused by the atomic bomb dropped on Hiroshima by the United States, is remembered for making more than 1,000 origami paper cranes in her hospital bed under the belief it would aid her recovery.

Now momentum is building for the cranes' inclusion in a U.N. register. Her older brother Masahiro, 81, and other relatives are preparing to submit her paper cranes, along with other items such as her handwritten notes, to a UNESCO documentary heritage program for registry in 2025 to mark 80 years since the end of World War II.

Masahiro and his second-eldest son Yuji, a 53-year-old nephew of Sadako, will apply to have the paper cranes added to UNESCO's Memory of the World Register.